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86 Trx250 Carb Questions

5K views 37 replies 5 participants last post by  shadetree 
#1 ·
Three questions as of now

I have an aftermarket carb currently and an original in rough shape but I can clean it up. Are all the jets in an aftermarket carb usable in the original?

Also right now it starts without choke cold and stalls when choke is turned on while running cold, which would imply it's running rich?

I have a problem with the idle fluctuating i did notice when I turn the handle bars to the right the engine will stall. The idle will fluctuate while sitting still. Are these related?

In the end I'd like to run the original carb. Thanks for the help

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#2 ·
Three questions as of now

I have an aftermarket carb currently and an original in rough shape but I can clean it up. Are all the jets in an aftermarket carb usable in the original?
Nope.

Also right now it starts without choke cold and stalls when choke is turned on while running cold, which would imply it's running rich?
Yep.

I have a problem with the idle fluctuating i did notice when I turn the handle bars to the right the engine will stall. The idle will fluctuate while sitting still. Are these related?
Sounds like the throttle cable is mis-adjusted or routed short... but with a china made carb, no one can predict how many things might be wrong with it? So its impossible to diagnose anything from here.

In the end I'd like to run the original carb.
Don't hesitate, do it now.

Thanks for the help
You're always welcome! If your original carb can't be saved let us know!
 
#3 ·
Three questions as of now

I have an aftermarket carb currently and an original in rough shape but I can clean it up. Are all the jets in an aftermarket carb usable in the original?
Nope.

Also right now it starts without choke cold and stalls when choke is turned on while running cold, which would imply it's running rich?
Yep.

Sounds like the throttle cable is mis-adjusted or routed short... but with a china made carb, no one can predict how many things might be wrong with it? So its impossible to diagnose anything from here.

In the end I'd like to run the original carb.
Don't hesitate, do it now.

Thanks for the help
You're always welcome! If your original carb can't be saved let us know!
I'm working on tearing it apart now so I can run it thru the machine at work but can't seem to get the throttle assembly apart.

How do I remove the part on the bottom shaft? I removed the rollpin just can't get it off. (Pic 1)

Does the cap on the other side have anything to do with it? (Pic 2)

Is the piece the needle goes thru removable? (Pic 3 sorry its upside down)

Not sure what its called but how do I remove it (Pic 4)


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#4 ·
oh man, your not suppose to remove the butter fly valve !. it's best to leave that alone. just remove all the jets, all rubber parts, drop it in your tank cleaner or how ever your gonna clean it ?, and put new jets/carb rebuild kit back in it. your gonna have one heck of a time pinging the butter fly valve screws now that you removed them.
 
#10 ·
Use compressed air to blow out all passages after the solvent bath and you should be good to go. Find a genuine Shindy kit for your carb if ya can... everything else is made in china and is useless.

You can reuse your original brass hard parts if you can get them clean without scratching or damaging them.

Use some JB-weld original formula epoxy on those butterfly screws when you reassemble it... center up the butterfly good so it closes without binding, then snug those two screws and wait 48 hours for the JB-weld to cure. It'll be perfect... no worries!
 
#13 ·
The factory service manual has a great recommended carb setup procedure. Get yourself a copy HERE if you haven't one handy yet. Note that you'll be synchronizing the butterfly & piston by bending a tab and don't forget to adjust all cables when you put it back on the motor. Check the carb boot for cracks too... old machines can have cracking boots that are difficult to spot until you stretch them open a bit.
 
#14 ·
The Shindy carb kit part number for an 86 Fourtrax TRX250 is: 03-017
Should cost you about $20 or so... make sure the kit you order is genuine Shindy, not fLeebay china knockoff crap.

Shindy Products, Inc. - ATV Replacement Parts

Don't use the fast setting JB-weld, use only the original formula stuff. For use in raw fuel you must allow the JB-weld to cure fully at room temperature for 48 hours minimum, rather than 24 hours as the instructions suggest. If your carb boot is cracking you can repair that using 3M Super-Fast urethane windshield sealer, which fully cures in 24 hours.

Keep a smile on... :) and let us know if we can help!
 
#17 ·
never used jb on anything that was worth it..lol. but, I would put it on the head to valve, and on the other side where the screw tip pokes through the butter fly valve, don't put it on the threads incase you have no reason to ever remove it later on ?.
 
#19 ·
I coat the holes and screw threads both with JB-weld. If you ever need to take those two screws back out for any reason, just heat them up to 550+ degrees (F) with a propane torch and easily unscrew them. JB-weld will last for decades in raw fuel environments as long as you use the slow setting stuff and allow 48 hours for a full cure. Works great in repairing missing well plugs in carbs, cracked floats, and pitted aluminum brake cylinder bores too.

I once fixed a cylinder bore (the wrist pin had lost its clip and the pin gouged the bore so deep it quit running mid-cut) on an old Homelite chainsaw that still runs great today... and that repair was done over 30 years ago!

:)
 
#22 · (Edited)
Yeah, number 21 is the baffle. I would put it back in the original carb if I were you. I'd plumb the drain hose and vent hoses correctly too. Now, if I were running a snorkel on the bike I'd plumb those vents differently to suit the snorkel, but on an all stock bike I'd return them to stock. Whatever you do... don't plug the bowl vents. They must sense atmospheric pressure for the carb to function.

EDIT:
You can buy 1/8" hose in about a 3 foot length at your local auto parts store, a Tee, a couple Ells maybe... and route your own vent lines. The service manual shows where they route to.
 
#25 ·
I bought the quad out of New York (I live in Michigan) on eBay for $350, not knowing if it ran or not but it looked nice so I planned on swapping my running motor into it (I have 2 250 fourtrax's) and selling it. Well turns out it ran, but slowly fixing things until it runs like I'd like it too. As far as I know so far I am only needing the Shindy kit, the baffle, and vent lines. I'll definitely be having the parts diagram next to during reassembly.
 
#26 ·
Sounds like you got a smokin' deal on it! Congrats!

It takes quite a while to set up a carb right even with the manual handy for reference. But you only have to do it once if you do it well! Keep ethanol out of it and that carb will be trouble-free and still be in great condition 30 years from now.

I hope to see some pics of the ole gal once you get it back in shape..? :)
 
#29 ·
Just to chime in... I had major needle valve issues with a 250 carb, changed 3 valves before I got it right, Honda UK still sell individual parts for these carbs but not rebuild kits.
Thought that it was worth mentioning incase you get any issues
 
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#32 ·
why would you need UK link, when your state side ???, most oem parts for your atv is discontinued today, either ebay, or salvage yard is your best bet, or after market, not much of a choice.
 
#33 ·
Honda UK are all franchises, give me a while and I’ll get some numbers for you. Honda UK still had individual carb parts for trx250a shady but wouldn’t supply a whole carb rebuild kit.
 
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#34 ·
I couldn’t get the numbers without opening them individually l, if you google any of those I’m sure you’ll find the parts your after.
Just remember the time difference, as I’m typing this it is currently 07:15, most places here in the UK open at 8am to 9am.
 

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#36 ·
You could use a number of ways to clean it.. Some guys use a vinegar solution, soda blasting, hydrochloric acid solution, phosphoric acid solution, brass wire wheel on a bench grinder...

If you go the route of using acid be sure to wash thoroughly with fresh water afterwards, even if you leave it soak or use soapy water, it’s of upmost importance.
 
#38 ·
you know it !!..lol. I use super clean all the time, that stuff works !!. it won't leave it shinny ?, but it sure will cut through all the gunk/dirt/ you name it. then a dremel with a wire wheel brush will make it shinny.
 
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